Absorption refrigeration system

ABSTRACT

AN ABSORPTION REFRIGERATION SYSTEM WHEREIN THERE IS PROVIDED FLUID TRANSFER APPARATUS COMPRISING A STATIONARY HERMETIC HOUSING HAVING A CYLINDRICAL NONFERROMAGNETIC WALL ENCASING ANNULAR ROTOR MEANS WITHIN THE HOUSING ABOUT WHICH A ROTATABLE SCOOP PUMP PAN IS CONNECTED FOR ROTATION THEREWITH FOR CIRCULATING ABSORBENT SOLUTION THROUGH THE SYSTEM. THE ROTOR IS SUPPORTED IN MAGNETICALLY INDUCTIVE RELATION THROUGH THE NONFERROMAGNETIC HOUSING WALL WITH AN ANNULAR STATOR LOCATED EXTERIORLY OF THE HERMETIC HOUSING. A SECOND ROTOR IS PROVIDED WITHIN THE CYLINDRICAL STATOR FOR DRIVEN A FAN FOR COOLING THE STATOR. THE SCOOP PUMP INCLUDES SECTIONS FOR PUMPING STRONG SOLUTION TO THE ABSORBER, WEAK SOLUTION TO THE GENERATOR, AND REFRIGERANT TO THE EVAPORATOR.

p 1971 w. w. BELL, JR 3,608,329

ABSORPTION REFRIGERATION SYSTEM Filed March 18, 1970 INVI'JNTOR.

WILLIAM w. BELL, JR.

ATTORNEY United States Patent 3,608,329 ABSORPTION REFRIGERATION SYSTEM William W. Bell, Jr., Marcellus, N.Y., assignor to Carrier Corporation, Syracuse, N.Y. Filed Mar, 18, 1970, Ser. No. 20,768 Int. Cl. F25b /06 US. Cl. 62-476 6 Claims ABSTRACT OF THE DISCLOSURE An absorption refrigeration system wherein there is provided fluid transfer apparatus comprising a stationary hermetic housing having a cylindrical nonferromagnetic wall encasing annular rotor means within the housing about which a rotatable scoop pump pan is connected for rotation therewith for circulating absorbent solution through the system. The rotor is supported in magnetically inductive relation through the nonferromagnetic housing wall with an annular stator located exteriorly of the hermetic housing. A second rotor is provided within the cylindrical stator for driving a fan for cooling the stator. The scoop pump includes sections for pumping strong solution to the absorber, weak solution to the generator, and refrigerant to the evaporator.

BACKGROUND OF THE INVENTION This invention relates to absorption refrigeration systerns. It is known to employ centrifugal pumps to circulate strong absorbent solution to an absorber, and to circulate weak absorbent solution to the generator, and to circulate refrigerant to an evaporator. Centrifugal pumps require that a positive head exist in order to force the liquid into the impeller eye without flashing and vapor binding. This available head at the pump intake is referred to as net positive suction head or NPSH, and the requirement for a minimum NPSH in centrifugal pumps adds undesirable height to the absorption machine and limits their application thereto.

Accordingly, it has been proposed to circulate absorbent solution and refrigerant in an absorption refrigeration system by using one or more scoop pumps generally taking the form of a closed chamber within which is rotatably mounted a rotor or peripherally flanged disc for centrifugally impelling at a high tangential velocity liquid directed into the chamber through an inlet conduit, the liquid which is thus flung outwardly being picked up by a scoop or eduction tube. Scoop pumps have among their advantages simplicity of construction and are generally completely self-balancing and normally will not cavitate even at low NPSH.

However, the prior drive arrangements for scoop pumps have presented certain problems. It is known to drive the scoop pumps by an exteriorly mounted motor having a shaft connected through a seal in the scoop pump housing but such seals are subject to leakage in use. It has also been proposed to drive a scoop pump by means of magnetic couplings connected to an exteriorly located motor. Whether the magnetic coupling be of radial drive or axial drive type, close tolerances are required in order to provide an efficient magnetic coupling and to avoid possible misalignment problems. However, in prior magnetic coupling arrangements, bearing or other wear, such as occasioned by axial thrusts impaired during operation, can result in interference and destruction of the coupling parts.

SUMMARY OF THE INVENTION In accordance with this invention, there is provided an absorption refrigeration machine, which embodies therein fluid transfer apparatus comprising a housing having a central, generally cylindrical, nonferromagnetic wall. An

annular rotor member is supported within the housing in surrounding relation with the cylindrical wall. A scoop pump, for circulating absorbent solution and refrigerant through the absorption refrigeration system, is secured to the annular rotor within the housing. An annular motor stator member is positioned in the cylindrical wall of the housing interiorly of which there may be positioned in coaxially spaced relation therewith a cylindrical auxiliary rotor driving fan means for air cooling the stator.

It can be seen from the foregoing that the rotative driving forces coupling the stator to the pump means comprises the motor itself, thereby eliminating the separate magnetic coupling or seal required with earlier arrangements. Further, the combined inverse motor and coupling of this invention can be easily air cooled, and as well, the bearing means can readily be lubricated by the fluid being pumped exteriorly of the motor housing.

BRIEF DESCRIPTION OF THE DRAWING The single view is a schematic flow diagram, partially in cross section, of an absorption refrigeration system embodying a fluid transfer apparatus in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment of this invention, there is provided an absorption refrigeration system which utilizes water as a refrigerant and an aqueous solution of lithium bromide as an absorbent. Strong solution as referred to herein is a concentrated solution of lithium bromide,- which is strong in absorbing power. Weak solution is a dilute solution of lithium bromide which is weak in absorbing power.

Referring now to the drawing, there is shown an absorption refrigeration system comprised of a generator 10, a refrigerant condenser 12, an absorber 14, an evaporator 16, a solution heat exchanger 18, and fluid transfer apparatus designated generally by the legend A. A purge unit 20 may be employed to remove relatively noncondensable vapors from the system.

Generator 10 comprises a boiler in which Weak absorbent solution is directed from heat exchanger 18 through conduit means 22, the solution being caused to boil in the generator by a heat source such as steam pipe 24 to concentrate the absorbent solution by vaporizing refrigerant, which passes into condenser 12 through passage 26.

Refrigerant condensed in condenser 12 is directed by conduit means 28 to evaporator 16. A heat exchanger 30 through which a heat transfer medium to be cooled flows, is located in the evaporator. A spray header 32 is also disposed in the evaporator to wet the surfaces of the heat exchanger 30 with liquid refrigerant recirculated from the evaporator. Refrigerant in evaporator 16 is evaporated to cool liquid passing through heat exchanger 30 and the water vapor passes through passage 34 to absorber 14.

Absorbent solution in absorber 14 absorbs water vapor from evaporator 16. Heat exchangers 36 and 38 are connected to a source of cooling medium, such as water, to remove waste heat from the refrigeration cycle. Also located in the absorber 14 is spray header 40 which serves to wet the surfaces of heat exchanger 36 with strong absorbent solution.

Fluid transfer apparatus A preferably comprises a stationary, generally cylindrical, and centrally located inner nonferromagnetic housing wall 42 to which is welded or otherwise secured as at 44 an annular outer hermetic housing 46. Secured to the inner walls of the stationary central housing 42 by welding or like techniques is an annular motor stator 48 disposed between opposite ends of the housing wall 42, and having windings indicated at 48a connected to a source of electrical power. The opposite ends of the housing support spider members or apertured plate members 50 and 52 having central hub portions 50a and 52a receiving shaft means 54 journaled at opposite ends in bearing means 56 and 58. An auxiliary motor rotor 60 is mounted on shaft 54 for rotation in response to energization of stator 48 from which it is coaxially spaced. Shaft means 54 carries thereon fan means 62 for effecting forced air flow through opposite open ends of housing 42 and across stator 48 to cool the same.

Fluid transfer apparatus A further includes an annular rotor 64 supported upon inner housing wall 42 by a pair of large diameter annular bearing means 66 and 68 i disposed at its opposite ends and in running relation with the outer diameter of the housing wall 42. Rotor 64 and the outer diameter of the inner housing wall 42 are slightly coaxially spaced from one another at 70 toprovide clearance therebetween. Rotor 64 and bearing means 66 and 68 are preferably supported for rotation within an annular casing 72 having an axially extending wall portion 76 integral with radially directed and axially spaced wall portion 78 and 80. Annular wall portion 76 provides support for the scoop pump structure. The bearing means 66 and 68 are desirably spaced slightly axially inwardly of the ends of the stationary housing 46 to provide a fluid flow path for solution and refrigerant and thus a convenient means of adequate bearing lubrication, particularly upon start-up of the'machine.

There is shown in the drawing a plurality of scoop pump means designated generally by the legends P1, P-2, and P-3, three pumps being provided in the exemplary embodiment shown, although obviously this number can be varied depending upon the particular functions to be performed. The scoop pump structure may be formed by a radially extending main wall member 82 having a flange portion 84 welded or otherwise secured to annular wall portion 76 of the rotor and bearing casing 72. A channelshaped scoop pump pan is formed by the opposite end of wall member 82 being connected to an axially directed wall portion 86 from which extends a radially inwardly directed wall portion 88. Also connected to the main member 82, as by welding, are a pair of channel-shaped pan or flange members 90 and 92 forming scoop pump pans. The scoop pump wall structure as shown and described defines a refrigerant circulation chamber 94 and a pair of solution circulation chambers 96 and 98. To pressure isolate the relatively high pressure chambers 96 and 98 from the relatively low pressure chamber 94, the annular hermetic housing 46 is provided interiorly with a flange portion 100 which cooperates with wall portion 88 of the chamber 96 to provide a hydrodynamic seal during operation.

Leading from evaporator 16 is inlet conduit means 102 having a discharge nozzle 10211 for transferring liquid refrigerant into evaporator circulation chamber 94 wherein it is centrifugally impelled and pumped therefrom through eduction orifice 104a of eduction conduit means 104 forming a part of scoop pump P-1. Solution circulation chamber 96 has fed thereto weak relatively cool solution from absorber 14 through inlet conduit 106 provided with a discharge nozzle 106a. Discharge nozzle 108a of pickup scoop 108 having an eduction orifice 10812 and a suitable loop therein for balancing pressure is provided for transferring to chamber 96 any fluid which might splash from the chambers 94, 96, or 98, into the housing and also to pump solution with or without refrigerant mixed therewith which drains into the housing bottom upon machine shutdown. The strong and weak solutions can intermix on shutdown, even though no significant amount of refrigerant combines therewith, and solution solidification is thereby effectively prevented. Weak solution is pumped from chamber 96 to generator by eduction passage 114 having eduction orifice 114a in pan 86.

Solution circulation chamber 98 has disposed therein discharge nozzle 11001 of inlet conduit means 110 for transferring thereto strong relatively hot solution from generator 10 through conduit 112 and solution heat exchanger 18. A degree of flash cooling takes place in the chamber 98, the flash vapors being absorbed by solution in chamber 96 to warm the solution therein, while the temperature of the solution in chamber 98 is reduced. Weak relatively warm solution is pumped from chamber 96 through eduction orifice 114a of eduction conduit 114 and transferred through solution heat exchanger 18, in counterflow heat transfer relation with strong solution passing therethrough, into generator 10 to be reconcen: trated therein. Simultaneously, strong solution is transferred from chamber 98 through eduction orifice 116a of eduction conduit 116 forming a part of scoop pump P-3 and is pumped to absorber 14 to be discharged therein through spray header 40. 7

It is to be seen from the foregoing that there is provided by this invention an absorption refrigeration system embodying fluid transfer or fluid circulation apparatus incorporating a motor wherein a stationary stator is positioned within a cylindrical nonferromagnetic housing wall connected exteriorly to an annular hermetic housing in which is located a rotatable rotor having pump means, desirably of the scoop type, connected thereto for circulating one or more fluids through the refrigeration system in response to rotor rotation magnetically induced by the stator. The pump drive means of this invention is of relatively simple construction, and the motor is enabled to directly drive the pump without use of a separate coupling or shaft seal. The stator can be readily air cooled, as has been disclosed, and replacement of the stator in the event of burn-out can be effected in the field with a minimum of effort without exposing the interior of the machine to atmosphere. In the arrangement shown, the bearings can be relatively large, thereby assuring longer life, and means are provided for lubricating the bearings with the fluids being pumped. Thrust load on the bearings is negligible with the preferred disposition of the parts on a horizontal axis, and further, the rotor is magnetically centered and tolerance and alignment problems of the prior art are substantially eliminated.

Various changes and modifications, additional to those disclosed herein, may be effected without departing from the scope of the invention as defined in the subjoined claims.

I claim:

1. An absorption refrigeration system comprising a generator for boiling absorbent solution to concentrate the solution. by vaporizing refrigerant therefrom; a condenser for condensing refrigerant vapor formed in the generator; an evaporator for evaporating refrigerant condensed in the condenser to provide refrigeration; and an absorber for absorbing refrigerant vapor formed in the evaporator into absorbent solution concentrated in the generator; wherein the improvement comprises fluid transfer apparatus for pumping liquid within the system, said fluid transfer apparatus comprising a hermetically sealed, stationary, housing having a cylindrical, nonferromagnetic, interior, wall portion; an annular electric motor rotor member mounted for rotation within said stationary sealed housing coaxially about the exterior of said cylindrical nonferromagnetic wall portion and in close proximity thereto; a scoop pump including a rotatable channel-shaped pan member disposed radially outward of and secured to said annular motor rotor member for rotation therewith within said housing, said scoop pump further including stationary liquid inlet passage means for introducing a liquid to be pumped into said pan member, and a stationary liquid eduction passage having an eduction orifice disposed in said pan to pick up liquid rotated therein to thereby pump said liquid to a desired location in said system; and an exteriorly cylindrical electric motor stator coaxially disposed in the cylindrical opening formed by the nonferro magnetic wall portion of said housing and in close proximity thereto for inductive coupling with the annular rotor member within the housing, said stator having means for connection with a source of electric power torotate the annular rotor member and the associated scoop pump pan member within said housing to pump said liquid during operation of the system.

2. An absorption refrigeration system as defined in claim 1 including bearing means disposed within said housing and associated with said motor rotor winding, said bearing means being in engagement with the exterior diameter of the cylindrical, nonferromagnetic wall of said housing.

3. An absorption refrigeration system as defined in claim 2 including passage means within said housing for lubricating said bearing with a liquid pumped by said scoop pump.

4. An absorption refrigeration system as defined in claim 1 wherein said cylindrical motor stator is also annular; and wherein said system includes a second motor rotor coaxially disposed in the annular opening within said annular motor stator, said second motor rotor being connected to drive an auxiliary piece of equipment associated with said system.

5,. An absorption refrigeration system as defined in claim 4 wherein said auxiliary piece of equipment includes a fan for passing air over said motor stator outside said housing.

6. An absorption refrigeration system as defined in claim 1 including a plurality of scoop pump pans coaxially secured with said annular motor rotor Within said housing, said pans being in vapor communication with each other; means for passing strong absorbent solution from the generator to one of said pans, and means for passing Weak absorbent solution from the absorber to the other of said pans, to thereby provide a rotary flash heat exchanger in said housing; means to pass the strong solution pumped through one of the eduction conduits to said absorber; and means to pass the weak absorbent solution through another eduction conduit to said generator.

References Cited UNITED STATES PATENTS 2,184,992 12/1939 Coons 415-89X 2,225,338 12/1940 Geiss 310-67UX 2,768,583 10/1956 Richard et al. 31067 WILLIAM F. ODEA, Primary Examiner P. D. FERGUSON, Assistant Examiner US. Cl. X.R. 

